Expression data from bone marrow of primary multiple myeloma patients

Drug resistance is a major obstacle in cancer therapy. The molecular mechanisms of drug resistance still remain largely elusive. Microarray analyses on paired primary myeloma samples at baseline and after therapy or at relapse showed that NEK2 was one of the most up-regulated genes in myeloma cells after high-dose chemotherapy or at relapse. By analyzing the published (> 2,500) microarrays and clinical datasets, we found that NEK2 expression is increased in many malignancies, and that high expression of NEK2 was associated with a shorter event-free and overall survival. Moreover, NEK2 expression was typically increased in tumors with aggressive subtype and advanced TNM stage. Our studies indicate that over-expressing NEK2 in cancer cells resulted in enhanced cell proliferation and drug resistance, whereas knockdown of NEK2 induced significant cancer cell death and growth inhibition. We found that NEK2 over-expression activates cell cycle progression and cell division through the stimulation of cell cycling genes CDC2/CCNB1 and PBK. Interestingly, NEK2-overexpression also activated the Wnt/β-catenin signaling pathway. We conclude that NEK2 represents a predictor for drug resistance and poor prognosis in cancers and could be a potential target for cancer therapy. Myeloma tumor cells from bone marrow aspirates were collected at baseline and after chemotherapy (pre-1st and pre-2nd bone marrow transplant, and pre-consolidation) for RNA extraction and hybridization on Affymetrix microarrays. We sought to define genes related to chemotheraputic resistance.